Use of dual-modality PET/CT significantly increases the number of patients with correctly staged NSCLC and thus has a positive effect on treatment.

Tumor staging with PET/CT is significantly more accurate than CT alone, PET alone, and side-by-side PET + CT. This diagnostic advantage translates into treatment plan changes in a substantial number of patients.

The aim of this study was to evaluate the clinical significance of combined fluorine-18 fluorodeoxyglucose positron emission tomography and computed tomography (FDG-PET/CT) in patients with lymphoma, and to compare the FDG-PET/CT staging results with those of FDG-PET and CT alone. Twenty-seven patients were studied. Each patient had clinical follow-up for >12 months and entered complete follow-up evaluation. Patient-based evaluation showed a sensitivity of 78% for CT alone, 86% for FDG-PET alone, 93% for CT and FDG-PET read side by side, and 93% for combined FDG-PET/CT imaging. Region-based evaluation showed a sensitivity for regional lymph node involvement of 61%, 78%, 91% and 96% respectively. FDG-PET/CT imaging is superior to CT alone ( P=0.02) and has additional benefit over FDG-PET alone due to exact anatomical localisation. We conclude that FDG-PET/CT imaging is accurate in re-staging lymphoma and offers advantages over separate FDG-PET and CT imaging.

Iodine kinetics and lesion dose per administered 131 I activity (LDpA) of differentiated thyroid cancer metastases were determined using 124 I PET. These data were analyzed to derive an optimized dosimetry protocol. Methods: We evaluated the timeactivity-concentration curves of 37 lesions in 17 patients who had undergone thyroidectomies. LDpA determination involved 124 I PET images acquired at 4, 24, 48, 72, and 96 h after intake of a capsule containing 20-40 MBq of 124 I. A combination of a linear and a monoexponential or a monoexponential function only parameterized the time-activity-concentration curves. The LDpAs, calculated using data from all 5 PET time points, served as reference. The lesions were classified into 3 groups, according to potential for cure with 131 I therapy: low (#5 Gy GBq 21 ; n 5 14), medium (between 5 and 10 Gy GBq 21 ; n 5 9), or high LDpAs (.10 Gy GBq 21 ; n 5 14). Using the reference approach, the differences in the empiric kinetic parameters within the LDpA groups were evaluated. The reference LDpAs were compared with those derived from only 2, 3, or 4 PET data points and from 1 adapted 2-point approach. Lin's concordance correlation coefficient (r c ) and the mean absolute percentage deviation in LDpAs were used to assess agreement between simplified and reference approaches. Results: The effective 124 I half-life, linear activity-concentration rate (a), and 24-h activity concentration (CpA) (the latter 2 per administered 124 I activity) differed significantly among the LDpA groups (P , 0.05). LDpAs correlated with 24-h CpAs (r 5 0.94, P , 0.001). Using the 4-, 24-, and 96-h measurements, a r c value of greater than or equal to 0.90 was found, and the mean absolute percentage deviation was less than or equal to 16%. Similar statistical values were obtained for the adapted approach, which was based on 24-and 96-h PET data points only. Conclusion: Lesion classification into LDpA groups was feasible using a single PET scan at ;24 h. Because of the highly variable kinetics, 1 additional measurement at ;96 h was needed to obtain a sufficiently reliable LDpA estimate. The adapted 24-96-h approach appears to be the optimal 124 I protocol and is a reliable simplification of the 5-point protocol.Key Words: PET; radionuclide therapy; dosimetry; iodine-124; differentiated thyroid cancer Several groups (1-5) have successfully used 124 I PET alone and with CT to guide postsurgical treatment and, in particular, radioiodine therapy in patients with differentiated thyroid carcinoma (DTC). Preradiotherapeutic 124 I PET is valuable in restaging disease; dosimetric analysis of the imaging data can identify the patients most likely to benefit from radioiodine therapy and can determine safe and effective individualized therapeutic activities of radioiodine.Our original ;20, and ;44 h after 124 I administration; sometimes a fourth scan was acquired at 96-144 h. However, to our knowledge, no group has yet published the results of any systematic investigation to determine the number and timing of PET sca...

This study gathered information about clinical PET/CT operations worldwide to help guide discussions on the use and standardization of clinical PET/CT. Methods: A Web-based survey of PET/CT users was initiated in November 2009 through e-mail advertising using Academy of Molecular Imaging databases. Recipients were asked 58 questions related to demographics (e.g., location, number of PET/CT systems, and staffing), PET/CT operations and use, and variations in 18 F-FDG oncology imaging protocols. Results: The responders were from centers in the Americas (71%), Europe (22%), AsiaPacific (6%), and Middle East (1%), with most responding sites representing public health care institutions (60%). PET/CT systems were most frequently installed in nuclear medicine departments (59%). Of the sites operating a PET/CT system, 16% had 10 y or more of stand-alone PET experience. About 40% of all sites operated at least 2 PET/CT systems. PET/CT was most frequently used for applications in torso or whole-body oncology (87%), radiation therapy planning (4%), cardiology (4%), and neurology (5%). The average interval of fasting before an 18 F-FDG PET/CT examination was 7 6 3 h (range, 4-12 h). Blood glucose levels were measured at 99% of sites, but acceptable maximal glucose levels varied substantially (an upper limit of 200 mg/dL was applied at .50% of the institutions). A weight-based radioactivity dose injection was performed at 44% of sites. The mean 18 F-FDG activity injected was 390 MBq (range, 110-585 MBq) for 3-dimensional PET of a 75-kg patient. The mean uptake time was 64 6 14 min (range, 20-90 min). Split protocols involving patient repositioning and adapted imaging parameters were used at 51% of sites. Only 41% used patient positioning aids. Intravenous or oral CT contrast material was used at 52% of sites in up to 25% of patients. Most sites (90%) measured maximum standardized uptake value as an index of tissue glucose use. Only 62% of sites provided a fully integrated PET/CT report. Conclusion: An international survey among clinical PET/CT users revealed significant variations in standard 18 F-FDG PET/CT protocols. This finding illustrates the need for continuous training and ongoing standardization in an effort to optimize PET/CT in oncology.